//
//  NSString+AES.m
//  EncryptionTools
//
//  Created by awh on 2019/7/16.
//  Copyright © 2019年 com.personal. All rights reserved.
//

#import "NSString+AES.h"
#import "NSData+Base64.h"
#import <CommonCrypto/CommonDigest.h>
#import <CommonCrypto/CommonCryptor.h>
#import <CommonCrypto/CommonHMAC.h>

static char base64EncodingTable[64] = {
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
    'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
    'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
    'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
};
@implementation NSString (AES)
-(NSString *)AES128Encrypt:(NSString *)plainText key:(NSString *)key
{
    char keyPtr[kCCKeySizeAES128 +1 ];
    memset(keyPtr, 0, sizeof(keyPtr));
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
    
    NSData* data = [plainText dataUsingEncoding:NSUTF8StringEncoding];
    NSUInteger dataLength = [data length];
    
    size_t bufferSize = dataLength + kCCBlockSizeAES128;
    unsigned char *buffer = malloc(bufferSize);
    size_t numBytesEncrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,
                                          kCCAlgorithmAES128,
                                          kCCOptionPKCS7Padding|kCCOptionECBMode,
                                          keyPtr,
                                          kCCBlockSizeAES128,
                                          NULL,
                                          [data bytes],
                                          dataLength,
                                          buffer,
                                          bufferSize,
                                          &numBytesEncrypted);
    if (cryptStatus == kCCSuccess) {
        NSData *resultData = [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
        return [NSString base64StringFromData:resultData length:[resultData length]];
        
    }
    free(buffer);
    return @"";
}
-(NSString *)AES128Decrypt:(NSString *)encryptText key:(NSString *)key
{
    char keyPtr[kCCKeySizeAES128 + 1];
    memset(keyPtr, 0, sizeof(keyPtr));
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
    
    //NSData *data = [GTMBase64 decodeData:[encryptText dataUsingEncoding:NSUTF8StringEncoding]];
    
    NSData *data=[NSData base64DataFromString:encryptText];
    
    NSUInteger dataLength = [data length];
    size_t bufferSize = dataLength + kCCBlockSizeAES128;
    unsigned char *buffer = malloc(bufferSize);
    
    size_t numBytesCrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt,
                                          kCCAlgorithmAES128,
                                          kCCOptionPKCS7Padding|kCCOptionECBMode,
                                          keyPtr,
                                          kCCBlockSizeAES128,
                                          NULL,
                                          [data bytes],
                                          dataLength,
                                          buffer,
                                          bufferSize,
                                          &numBytesCrypted);
    if (cryptStatus == kCCSuccess) {
        NSData *resultData = [NSData dataWithBytesNoCopy:buffer length:numBytesCrypted];
        return [[NSString alloc] initWithData:resultData encoding:NSUTF8StringEncoding];
    }
    free(buffer);
    return @"";
}
+ (NSString *)base64StringFromData: (NSData *)data length: (NSUInteger)length {
    unsigned long ixtext, lentext;
    long ctremaining;
    unsigned char input[3], output[4];
    short i, charsonline = 0, ctcopy;
    const unsigned char *raw;
    NSMutableString *result;
    
    lentext = [data length];
    if (lentext < 1) {
        return @"";
    }
    result = [NSMutableString stringWithCapacity: lentext];
    raw = [data bytes];
    ixtext = 0;
    
    while (true) {
        ctremaining = lentext - ixtext;
        if (ctremaining <= 0) {
            break;
        }
        for (i = 0; i < 3; i++) {
            unsigned long ix = ixtext + i;
            if (ix < lentext) {
                input[i] = raw[ix];
            }
            else {
                input[i] = 0;
            }
        }
        output[0] = (input[0] & 0xFC) >> 2;
        output[1] = ((input[0] & 0x03) << 4) | ((input[1] & 0xF0) >> 4);
        output[2] = ((input[1] & 0x0F) << 2) | ((input[2] & 0xC0) >> 6);
        output[3] = input[2] & 0x3F;
        ctcopy = 4;
        switch (ctremaining) {
            case 1:
                ctcopy = 2;
                break;
            case 2:
                ctcopy = 3;
                break;
        }
        
        for (i = 0; i < ctcopy; i++) {
            [result appendString: [NSString stringWithFormat: @"%c", base64EncodingTable[output[i]]]];
        }
        
        for (i = ctcopy; i < 4; i++) {
            [result appendString: @"="];
        }
        
        ixtext += 3;
        charsonline += 4;
        
        if ((length > 0) && (charsonline >= length)) {
            charsonline = 0;
        }
    }
    return result;
}

@end
